The present invention relates to the use of a wood preservative for the supplemental protection of wood, comprising a copper compound, an alkanolmonoamine and a complexing organic carboxylic acid or its ammonium or alkali metal salts and a wrap for the supplemental protection of wood which contains this wood preservative.
For the supplemental maintenance of transmission poles existing in the grid of telephone and electricity-supplying companies, or similar poles, wraps with water-soluble wood preservatives are applied in particular in the groundline region. It is known to employ, for this purpose, water-soluble salts based on inorganic fluorine compounds, e.g. alkali metal fluorides, in some cases together with alkali metal bichromate or boron compounds such as boric acid or borax. However, these salts act exclusively against wood-destroying Basidiomycetes, while not providing an activity against soft rot for applications which involve contact with the soil. Substances which have been proposed as active against soft rot are, on the one hand, dinitrophenol (Barry A. Richardson: Wood preservationxe2x80x94The Construction Press Ltd., Lancaster p. 181) or combinations of the abovementioned compounds with water-soluble copper salts, e.g. copper sulfate or copper acetate. Mixtures of copper sulfate, also in combination with alkali bichromate, with boric acid and copper acetate with alkali fluoroborates are part of the prior art. In the meantime, dinitrophenol has been excluded due to its toxicity.
The water-soluble abovementioned copper compounds, alone, but also in the abovementioned combinations, do not have good diffusion properties for sufficiently penetrating for example the sapwood of pine poles, also during long standing times, and to reach the heart.
Wood preservatives based on copper and amines as complexing agent have been proposed for large-scale impregnation, in particular boiler pressure impregnation.
EP-B-211 181 relates to a wood preservative based on a copper salt and monoethanolamine for the boiler pressure impregnation of wood.
EP-B 270 848 describes a wood preservative based on a copper compound, a carboxylic acid and an aliphatic polyamine for boiler pressure impregnation.
EP-A 423 674 describes a wood preservative based on a metal salt of an N-organyldiazeniumdioxy compound and a complexing polymeric amine for the boiler pressure method.
All the above-described wood preservatives feature high copper fixation potential in the wood. This limits the diffusibility of the copper, which is why these systems are not suitable for the supplemental protection of wood.
xe2x80x9cKnown, currently used systems for the supplemental protection of wood contain, for example, combinations of copper naphthanate, boron compounds and fluorine compounds. An example of this product type which is used mainly in the USA is CuRAP 20 (ISK Biotech), a paste containing 18.16% of amine-based copper naphthenate and 40% of sodium tetraborate decahydrate. Analyses on poles (wood species: Douglas-fir and pine), which have been treated with this product, showed that, after 1 to 3 years of application, most of the copper is distributed virtually only in the outer zone (0-10 mm) in the wood (depth of penetration analyzed: up to 25 mm) and these products thus only have a very limited diffusibility as regards copper (Conserving energy by environmentally acceptable practices in maintaining and procuring transmission poles. 15th annual report, September 1995, J. J. Morrell, Oregon State University, Corvallis, Oreg.).xe2x80x9d
WO 96/23636 describes wood preservatives in paste form which comprise a fungicidal metal compound and a fungicidal boron compound. The metal compounds also embrace copper complexed with aminocarboxylic acids or polycarboxylic acids.
WO 96/23635 describes a wood preservative which comprises a metal chelate. Described are copper complexes with amino acids, iminodiacetic acid, ethylenediaminotetraacetic acid, dicarboxylic acids and polyphosphates.
The copper complexes with nitrogen-containing complexing polycarboxylic acids, e.g. imidodiacetic acid, ethylenediaminotetraacetic acid or nitrilotriacetic acid, do not become fixed in wood, but are leached completely from the wood (WO 96/23635, page 20, Table 6) and thus diffuse from wood into the environment when exposed to moisture (weathering, contact with the soil), which not only means increased pollution, but, as time goes by, the wood is not protected sufficiently against soft rot. This also applies to other complexing acids such as the hydroxycarboxylic acids, e.g. citric acid, malic acid and tartaric acid.
In contrast, copper chelates with other dicarboxylic acids, for example phthalic acid, maleic acids, lack sufficient diffusibility.
Thus, formulations based on the abovementioned substances alone are not ideally suited for the supplemental protection of wood.
German Patent Application DE-A 196 08 435 describes the use of a wood preservative for the supplemental protection of wood which comprises a copper compound, a polyamine and an inorganic fungicide.
It is an object of the present invention to provide a wood preservative for the supplemental protection of wood which features good diffusibility of the copper in the wood combined with good protection against soft rot and Basidiomycetes.
It is a further object of the present invention to provide a wrap which comprises this wood preservative for the supplemental protection of wood.
We have found that these objects are achieved by a wood preservative, for the supplemental protection of wood, based on a copper compound, an alkanolmonoamine and a complexing organic carboxylic acid or its ammonium or alkali metal salts and, if appropriate, further auxiliaries and, if appropriate, water.
For the sake of simplicity, all or some of the copper compound may also be present in the form of the salt of the complexing organic carboxylic acid (e.g. copper citrate, copper tartrate).
To improve the activity, inorganic fungicides may also be admixed to the wood preservative as a complement.
These wood preservatives are especially suitable for the supplemental protection and supplemental maintenance of wood and are used in the form of wraps and by the injection inoculation-method, the drilled hole method and the paste method. In the presence of moisture, e.g. ground contact, they penetrate the sapwood, and they have a good depth action.
Copper compounds which can be used are compounds which are soluble or insoluble in water, e.g. copper sulfate, copper acetate, copper citrate, copper tartrate, copper naphthenate, copper hydroxide, copper hydroxycarbonate, copper oxychloride, copper oxide, copper borate, copper fluoride, copper fluoroborate, bis(N-cyclohexyldiazeniumdioxy)copper, or mixtures of these.
Preferred are copper hydroxycarbonate, copper hydroxide and mixtures of these.
Copper hydroxide, specifically stabilized copper hydroxide (Norddeutsche Affinerie), is especially preferably used.
The activity of the wood preservatives can be improved by the salts of N-cyclohexyldiazenium dioxide and other diazenium dioxides, e.g. as the potassium salt, in which case, as a rule, the abovementioned bis(N-cyclohexyldiazeniumdioxy)copper is formed with copper compounds.
The mixtures comprise from 0.25 to 15% by weight of copper, calculated as the element. Some of the copper can also be replaced, for example by a corresponding zinc compound.
The following can be used as alkanolmonoamines: monoalkanolmonoamines, dialkanolmonoamines, trialkanolmonoamines having 2 to 18 C atoms, and Nxe2x80x94C1-C4-monoalkylmonoalkanolmonoamines, Nxe2x80x94C1-C4-dialkylmonoalkanolmonoamines, Nxe2x80x94C1-C4-monoalkyldialkanolmonoamines and mixtures of these.
Suitable examples are: monoethanolamine, diethanolamine, triethanolamine, 3-aminopropanol, monoisopropanolamine, 4-aminobutanol, monomethylethanolamine, dimethylethanolamine, triethylethanolamine, monoethylethanolamine, N-methyldiethanolamine and mixtures of these.
The following are preferably used: monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, and mixtures of these.
Monoethanolamine is especially preferably used.
Examples of complexing organic carboxylic acids which are used are hydroxycarboxylic acids, aminocarboxylic acids, nitrogen-containing polycarboxylic acids, the ammonium or alkali metal salts of these, and mixtures of these.
Examples of suitable hydroxycarboxylic acids which can be used are glycolic acid, lactic acid, tartaric acid, citric acid, malic acid, their ammonium or alkali metal salts, and mixtures of these.
Amino acids, e.g. glycine, sarcosine, the ammonium or alkali metal salts of these and mixtures of these may also be used.
Examples of suitable nitrogen-containing complexing polycarboxylic acids which can be used are nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DPTA), propylenediaminetetraacetic acid (PDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), xcex2-alaninediacetic acid, the ammonium or alkali metal salts of these and mixtures of these.
Hydroxycarboxylic acids are preferably used, because they are environmentally friendly. Citric acid is especially preferred in this context.
Suitable inorganic fungicides are boron compounds such as alkali metal borates, aminoborates, boric acid, boric esters and B2O3; fluorides such as alkali metal fluorides, alkali metal bifluorides, silicon fluorides, ammonium fluorides, ammonium hydrogen fluorides; fluoroborates, fluorophosphates, difluorophosphates, and mixtures of these.
The following are preferred: sodium fluoroborate, potassium fluoroborate, boric acid, sodium fluoride and mixtures of these.
The wood preservatives of the present invention can additionally comprise auxiliaries such as water, binders, paste formers, organic and inorganic bases, aliphatic carboxylic acids, the ammonium or alkali metal salts of these, plasticizers, fillers, wetters, thickeners and mixtures of these.
The wood preservatives may additionally comprise water for modifying the viscosity and for handling.
Examples of substances which can be used as binders and paste formers are acrylate resins in the form of aqueous dispersions or powders; plastisols, aminoplasts, phenoplasts, PVC with plasticizers, and mixtures of these.
Organic and inorganic bases which can be used are ammonia, alkali metal hydroxide solution, amines, or mixtures of these. Examples of suitable amines are mono-, di- and trialkylamines, and also poyamines.
The following may additionally be used for improving the flexibility of the wood preservative dried onto a support material: aliphatic C5-C20-carboxylic acids such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, 2-ethylenepentanoic acid, 2-ethylhexanoic acid, 2-ethylheptanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, versatic acids (highly branched monocarboxylic acids), dicarboxylic acids (C5-C20), e.g. decanedicarboxylic acid, sebacic acid. Also suitable are polycarboxylic acids such as polyacrylic acids or copolymers of acrylic acid and, for example, maleic acid and naphtenic [sic] acid.
Suitable wood preservatives comprise, for example,
2-50% by weight, preferably 5-40% by weight, of a copper compound,
2-60% by weight, preferably 5-50% by weight, of an alkanolmonoamine,
1-65% by weight, preferably 2-55% by weight of a complexing organic carboxylic acid or an ammonium or alkali metal salt thereof,
0-50% by weight, preferably 5-50% by weight of an inorganic fungicide,
0-25% by weight, preferably 1-20% by weight of an alkali metal salt of N-cyclohexyldiazenium dioxide,
0-25% by weight, preferably 1-20% by weight of an auxiliary,
0-50% by weight, preferably 1-40% by weight of water,
the total of all components being 100% by weight.
The following wood preservatives have proven themselves:
a) 5-40% by weight of a copper compound,
5-60% by weight of an alkanolamine,
5-35% by weight of a complexing organic carboxylic acid,
5-50% by weight of an inorganic fungicide,
2.5-50% by weight of water,
or, specifically when using binders and paste formers,
a) 5-40% by weight of a copper compound,
5-60% by weight of an alkanolamine,
5-35% by weight of a complexing organic carboxylic acid,
5-50% by weight of an inorganic fungicide,
0-5% by weight of an alkali metal salt of N-cyclohexyldiazenium dioxyl [sic],
5-40% by weight of an auxiliary,
0-30% by weight of water.
The wood preservatives, which may be present in the form of concentrates or, diluted with water, as viscous solutions or in the form of pastes, if appropriate also as solid salts, are best prepared by dissolving an alkanolmonoamine and a complexing organic carboxylic acid, if appropriate using water and/or auxiliaries, and treating the stirred solution with the copper compound.
The copper compounds then dissolve in this mixture, forming complexes.
This premix may already exist in the form of a highly concentrated paste to which the inorganic fungicides and, if appropriate, other auxiliaries are then added, with stirring.
The residual fixation of the copper can be adapted to the use conditions by altering the alkanolamine/acid ratio.
The pH of the wood preservative in the form of the concentrate or paste is generally from pH 7-12. The concentrates or pastes can be applied to or incorporated into a suitable support material either directly or with the addition of a binder, depending on the purpose in question. Examples of suitable support materials are polymer films or formed fabrics, e.g. made of glass fiber, polypropylene, polyester fiber, viscose fiber, foam plastics or other porous polymer compositions. The concentrates are applied to the support material for example by rolling (calendering). Examples of substances which may be used as binders are acrylate resins in the forms of aqueous dispersions, powders; plastisols, aminoplasts, phenoplasts, PVC with plasticizers.
In most cases, the concentrate/support system is subsequently dried, for example in the air or, for example in an oven at from approximately 100 to 180xc2x0 C., the concentrate drying to a highly viscous consistency and being bound to the support; if appropriate, this binding can be improved by the addition of the abovementioned binders; if necessary, this can simultaneously reduce the release of wood preservative after application if the binder is employed at high dosage rates.
The concentrates, in particular when adding binders, may also be extruded, dried and cut to size in order to obtain salt cartridges for insertion into wood via drilled holes, for example when using the drilled hole method. Also, it is possible to make cartridges of pulverulent mixtures, for example when using spray-dried concentrates or when using pulverulent raw materials in the form of pressed articles consisting of salt.
The diffusible pastes and concentrates or cartridges can be applied in the various processes of supplemental protection and supplemental maintenance, when the aim is to achieve larger amounts of protectant introduced and deeper penetration depth in the case of wooden components which are particularly at risk.
The pastes are suitable for the wrap method, such as single wraps or multiple wraps, the injection inoculation method, the drilled hole method and the paste method.
Application is carried out in the form of preventive or else curative protective treatments for the following purposes:
a) to impart long-term protection to certain sections of timber which is otherwise not treated with wood preservatives, e.g. ceiling beam heads;
b) to increase, in the danger zones, the amounts introduced or penetration depth achieved by the initial treatment;
c) to supplement or increase the protectant content of the basic protection in wood already used in existing constructions after prolonged standing time (time of use);
d) to reach, in wooden components used in existing constructions, even those zones which cannot be reached with customary soaking methods, in particular when carrying out a curative measure.